MILWAUKEE, March 22 (UPI) -- Researchers have discovered some of the oldest evidence of multicellular organisms.
Scientists hope the newly discovered marine algae fossils, ancient ancestors of seaweed, will provide clues as to the early evolution of animals on Earth from single-celled to multicellular organisms.
The fossils are at least 555 million years old, dated to the Ediacaran period, the latter part of the Precambrian eon. The fossil was excavated in Mongolia.
Their discovery lends credibility to scientists who believe the origins of multicellular organisms lie much earlier than previously thought.
"This discovery helps tell us more about life in a period that is relatively undocumented," University of Wisconsin-Milwaukee paleontologist Stephen Dornbos said in a news release. "It can help us correlate the changes in life forms with what we know about the Earth's ancient environments. It is a major evolutionary step toward life as we know it today."
Most ancient soft-bodied organisms, such as the recently unearthed algae fossils, are found among Burgess Shale-type deposits. And most BST deposits are dated to the Cambrian period, the time when researchers believed multicellular life first flourished -- the so-called Cambrian explosion or Cambrian radiation.
While the latest discoveries -- detailed in the journal Scientific Reports -- hint at a more complex narrative, researchers say identifying Precambrian organisms, let alone drawing larger conclusions, is difficult given the dearth of geologic evidence.
"If you find a fossil from this time frame, you really need strong support for your interpretation of what it was," Dornbos said. "And the farther back you go in geologic time, the more contested the fossil interpretations are."